# Mathematical Dictionary - Letter E

SYMMETRY AXIS - The line that separates a figure from its reflection or bounce.

AXES - When plotting the coordinates or graph in 2 dimensions, we use 2 axes, x horizontally and y vertically. When in space there is one more axis perpendicular to the plane xy, the new axis is called z.

X AXIS - The horizontal axis in an orthogonal Cartesian system. Location where the abscissa is marked from any point.

Y AXIS - The vertical axis in an orthogonal Cartesian system. On this axis the ordinates are marked.

Z AXIS - The axis that has representation in space and is perpendicular to the plane formed by the axes of x and of y. It is usually displayed upright.

ELEMENT - An object in a set is an element of this set.

NEUTRAL ELEMENT - In an operation is the element that has no influence on the final result. The neutral element in addition is zero in multiplication and division is 1. Examples: 5 0 = 5; 7 x 1 = 7. In logical operations: A U = A; THE  = A.

ELLIPSE - Flat curve where the sum of the distances from any point to two points called foci remain constant. ENEAGON - A 9-sided polygon.

LIST - Associate objects in a unique way with natural numbers.

EQUATION - Algebraic expression indicated by an equality, where there are unknown values ​​expressed by letters (unknowns).

EXPONENTIAL EQUATION - An equation where the unknown figures as exponent. Example: y = 3x.

FACTIONAL EQUATION - An equation where the independent variable figures in denominator.

LINEAR EQUATION - It is an equation of the form ax + b = 0, where a and b are numbers. A linear relationship can be expressed with the expression y = ax + b which represents, in a Cartesian system, a line.

EQUIVALENTS - Which is of the same value. That which is equivalent.

SCALE - The reason that compares, on a map, the distance on the map with the actual distance.

SPHERE - A figure formed by the set of all points in three-dimensional space, equidistant from a fixed point called the center of the sphere, by a fixed distance known as the radius of the sphere.

SQUARE - Drawing instrument in the shape of a rectangle triangle.

STATISTIC - Part of mathematics that organizes and presents numerical information, and draws conclusions from that information.

ESTIMATE OR ESTIMATE - Attitude to estimate a numerical result. It is the approximate result of an operation. It can be done mentally or in writing. Although we know that = 3.1415926535… we can estimate the value of Pi as the division of 22 by 7.

NUMBER EXPRESSION - Sequence of numerical operations indicated, ie not performed.

Eccentricity - Reason used in some definitions of a conic.

A - B - C - D - E - F - G - H - I / J / K - L - M - N - O - P - Q - R - S - T - U / V - X / Z